It is known to convert olefins having 3 or 4 carbon atoms per molecule (C.sub.3 and C.sub.4 olefins) in two stages in the presence of catalysts containing nickel or catalytically active metal and ZSM-5 as crystalline molecular sieve material, in order to produce dimers from olefinic feed molecules in the first stage and subsequently converting said dimers in the second stage to higher boiling hydrocarbons such as tetramers of C.sub.3 - or Chd 4- olefins.
It is furthermore known to apply crystalline aluminum silicates (e.g. mordenite) in which one or more catalytically active metals have been incorporated, in a wide variety of hydrocarbon conversion processes, including oligomerization.
A problem associated with the use of olefins-containing feeds in catalytic processes in general, and in particular in dimerization and oligomerization processes as described herein before is the catalyst stability which is often negatively influenced by undesirable compounds such as dienes which are in many cases present in olefinic feeds available in refineries.